U.S. Pat. No. 5,831,521 to the same inventor of this application disclosed an automatic emergency signal device having a movable weight movable in a casing mounted in a vehicle, a sensor actuated by the movable weight due to inertia of the movable weight upon a sudden or emergency braking of the vehicle for sensing a trigger signal which in then treated by a controller for lighting up a warning light.
However, when the vehicle is driven to climb up a slope, the movable weight is inclined downwardly backwardly due to its gravity, thereby resisting a forward movement of the weight to actuate the sensor and the warning light and therefore influencing the precision and reliability of the signal means.
Similarly, when the car is driven down a slope, the movable weight will be suddenly rolled forwardly due to a forward inclination of the car and the signal means to cause a false actuation of the warning light, possibly losing its warning effect even an emergency braking is not yet done.
The present inventor has found the drawbacks of the conventional emergency signal means and invented the present self-compensational automatic signal means for vehicles.